Impact of Optimal Unified Power Flow Controller in Electrical Transmission Systems in Reducing Transmission Cost

This paper presents an approach to optimal placement of optimal unified power flow controller (OUPFC) in electrical transmission systems utilizing genetic algorithm (GA), while reducing transmission systems cost using MATLAB and MATPOWER. The proposed approach is based on optimal power flow (OPF) considering optimization of power systems operation conditions. In order to determine the appropriate place for installation of OUPFC, while considering power injection model of this controller, OPF is utilized to obtain multi-objective function of the optimization problem. In this regard, the objective function comprises generation cost, transmission cost, and OUPFC installation cost. The proposed approach is applied to IEEE 30-bus test system, where the obtained results demonstrate remarkable reduction in overall cost of power system.     

Secure multiobjective real and reactive power allocation of thermal power units

This paper presents best weight pattern evaluation approach to solve multiobjective load dispatch (MOLD) problem which determines the allocation of power demand among the committed generating units, to minimize a number of objectives. Operating cost, minimal impacts on environment, active power loss, are the objectives undertaken to be minimized subject to physical and technological constraints. MOLD problem is decomposed in two stages and is solved sequentially. In first stage, a optimization problem having multiple objectives which are function of only active power generation like operating cost, gaseous pollutant emissions, is solved to get optimal dispatch of active power generation, subject to meet the active power demand, generators’ capacity constraint and transmission active power line flow limits. In second stage, the system real power loss which is a function of reactive power generation is minimized, to get optimal reactive power generation, subject to meet reactive power demand, reactive power generators’ capacity constraint and transmission reactive power line flow limits, when active power generation is known in prior from first stage. The validity of the proposed method is demonstrated on 11-bus, 17-lines and 30-bus, 41-lines IEEE power systems.     

Quantum-Inspired Evolutionary Algorithm for Real and Reactive Power Dispatch

This paper presents an evolutionary algorithm based on quantum computation for bid-based optimal real and reactive power (P-Q) dispatch. The proposed quantum-inspired evolutionary algorithm (QEA) has applications in various combinatorial optimization problems in power systems and elsewhere. In this paper, the QEA determines the settings of control variables, such as generator outputs, generator voltages, transformer taps and shunt VAR compensation devices for optimal P-Q dispatch considering the bid-offered cost. The algorithm is tested on the IEEE 30-bus system, and the results obtained by the QEA are compared with those obtained by other modern heuristic techniques: ant colony system (ACS), enhanced GA and simulated annealing (SA) as well as the original QEA. Furthermore, in order to demonstrate the applicability of the proposed QEA, it is also implemented in a different problem, which is to minimize the real power losses in the IEEE 118-bus transmission system. The comparisons demonstrate an improved performance of the proposed QEA.      

Optimal reactive power dispatch using ant colony optimization algorithm

This paper proposed a procedure to solve the optimal reactive power dispatch (ORPD) problem using ant colony optimization (ACO) algorithm. The objective of the ORPD problem is to minimize the transmission power losses under control and dependent variable constraints. Proposed sensitivity parameters of reactive power at generation and switchable sources are derived based on a modified model of fast decoupled power flow. The proposed ACO-based algorithm is applied to the IEEE standard 14-bus, 30-bus systems, and a real power system at West Delta Network as a part of the Unified Egyptian Network. The obtained simulation results are compared with those of conventional linear programming, genetic algorithm, and particle swarm optimization technique. Simulation results show the capability of the proposed ACO-based algorithm for solving the ORPD problem, especially with increasing the system size.     

Optimal Power Flow Using a Hybrid Optimization Algorithm of Particle Swarm Optimization and Gravitational Search Algorithm

Abstract—This article presents a hybrid algorithm based on the particle swarm optimization and gravitational search algorithms for solving optimal power flow in power systems. The proposed optimization technique takes advantages of both particle swarm optimization and gravitational search algorithms by combining the ability for social thinking in particle swarm optimization with the local search capability of the gravitational search algorithm. Performance of this approach for the optimal power flow problem is studied and evaluated on standard IEEE 30-bus and IEEE 118-bus test systems with different objectives that reflect fuel cost minimization, voltage profile improvement, voltage stability enhancement, power loss reduction, and fuel cost minimization with consideration of the valve point effect of generation units. Simulation results show that the hybrid particle swarm optimization–gravitational search algorithm provides an effective and robust high-quality solution of the optimal power flow problem.     

Solution of optimal reactive power dispatch of power systems using hybrid particle swarm optimization and imperialist competitive algorithms

Management of reactive power resources is essential for secure and stable operation of power systems in the standpoint of voltage stability. In power systems, the purpose of optimal reactive power dispatch (ORPD) problem is to identify optimal values of control variables to minimize the objective function considering the constraints. The most popular objective functions in ORPD problem are the total transmission line loss and total voltage deviation (TVD). This paper proposes a hybrid approach based on imperialist competitive algorithm (ICA) and particle swarm optimization (PSO) to find the solution of optimal reactive power dispatch (ORPD) of power systems. The proposed hybrid method is implemented on standard IEEE 57-bus and IEEE 118-bus test systems. The obtained results show that the proposed hybrid approach is more effective and has higher capability in finding better solutions in comparison to ICA and PSO methods.     

Optimal generation dispatch with renewable energy embedded using multiple objectives

Traditional economic dispatch focuses mainly on minimizing the total operation cost of the power system. With the appearance of energy crisis and environmental pollution becoming a public issue, environmental effect of generator should be taken into consideration through the dispatch process. In this paper a multi-objective dispatch problem considering the integration of wind power is solved whose objectives include the generation cost, the reserve capacity and the environmental emission. To compromise different objectives, a coordination degree combined with a satisfaction degree are introduced in order to transform the multi-objective dispatch problem into a single-objective one, i.e., the optimal generation dispatch (OGD) model. Then the OGD is solved by a particle swarm optimization algorithm on an IEEE 30-bus system, with wind power generation and coal-fired generation embedded. The simulation results show that better results in terms of all the three objectives can be obtained from the OGD model, in comparison with two other multi-objective dispatch models. The simulation results also show that the integration of wind power will cause the increase of both the generation cost and the reserve capacity but will decrease the environmental emission.     

基于混沌遗传混合优化算法的短期负荷环境和经济调度

环境和经济短期负荷调度主要由在调度周期内的最优机组组合和负荷分配组成,该文将优先次序法、遗传算法与混沌优化相结合,以应用到电站机组环境／经济运行优化问题中,在混沌遗传算法中采用递阶基因结构,将控制基因用于机组组合全局粗寻优,参数基因用于负荷分配局部优化, 基因修正与罚函数相结合解决约束问题,采用混沌扰动避免遗传算法早熟,运用基于线性搜索的混沌局部优化方法,加快算法的收敛速度和降低计算时间,优化计算结果可以同时得到最优机组组合及负荷最优分配,为实际调度系统提供了一个良好的方法。     

Artificial bee colony algorithm for solving multi-objective optimal power flow problem

This paper presents a new and efficient method for solving optimal power flow (OPF) problem in electric power systems. In the proposed approach, artificial bee colony (ABC) algorithm is employed as the main optimizer for optimal adjustments of the power system control variables of the OPF problem. The control variables involve both continuous and discrete variables. Different objective functions such as convex and non-convex fuel costs, total active power loss, voltage profile improvement, voltage stability enhancement and total emission cost are chosen for this highly constrained nonlinear non-convex optimization problem. The validity and effectiveness of the proposed method is tested with the IEEE 9-bus system, IEEE 30-bus system and IEEE 57-bus system, and the test results are compared with the results found by other heuristic methods reported in the literature recently. The simulation results obtained show that the proposed ABC algorithm provides accurate solutions for any type of the objective functions.     

基于改进遗传模拟退火算法的PMU优化配置

分析了遗传算法和模拟退火算法的优缺点,将具有较好全局寻优性能的遗传算法和具有较强局部搜索能力的模拟退火算法结合,形成的遗传模拟退火MGASA算法用于解决以电力系统状态完全可观测和PMU配置数目最小为目标的PMU优化配置问题.在寻优过程中,先将每一代群体进行遗传操作,再对产生的新群体中各个体进行模拟退火操作,同时在选择、交叉、变异和复制操作过程中实施最优保留策略,复制策略采用Metropolis判别准则.通过采用IEEE14和IEEE39节点系统对该算法进行验证表明,MGASA算法在解决PMU优化配置问题上具有较高的寻优性能和搜索效率.     

Unit commitment using a hybrid model between Lagrangian relaxation and genetic algorithm in competitive electricity markets

This paper presents a hybrid model between Lagrangian relaxation (LR) and genetic algorithm (GA) to solve the unit commitment problem. GA is used to update the Lagrangian multipliers. The optimal bidding curves as a function of generation schedule are also derived. An IEEE 118-bus system is used to demonstrate the effectiveness of the proposed hybrid model. Simulation results are compared with those obtained from traditional unit commitment.     

New optimal placement of capacitors and dispersed generators using bacterial foraging oriented by particle swarm optimization algorithm in distribution systems

The shunt capacitor devices are utilized in distribution systems to possibly reduce reactive component of power losses. Besides, the dispersed generator (DG) units can be used to supply active power of loads and reduce active component of power losses. In this paper, by applying the multi-objective problem, optimal placements of these devices are determined based on bacterial foraging (BF) oriented by particle swarm optimization (PSO) algorithm (BF-PSO). The considered objective function includes the cost reduction of power losses and installation costs of shunt capacitor devices and DG units. Also, the problem solution at different load levels and the utilization of capacitor discrete values are performed for optimization. Finally, the proposed method is compared with genetic algorithm (GA), differential evolution (DE), and PSO methods. They are investigated on the IEEE 69-bus distribution system. The simulation results indicate the advantages of the proposed method for the optimization problem.     

电力系统动态经济调度优化问题的膜计算方法

将膜计算方法用于求解电力系统动态经济调度优化问题。首先利用二次罚函数将多约束经济调度问题转化为无约束优化问题,对于膜计算的3个基本要素——膜内对象、膜结构和进化规则,该方法以各发电机组24时段的出力值作为膜内对象;采用具有嵌套结构的类细胞膜型膜结构,包含并行基本膜和拟高尔基体膜;在基本膜内执行交叉规则、变异规则、修正规则和保留规则,拟高尔基体被激活后执行移位规则、提取规则和目标导向规则。通过膜内对象不断进化择优,从而实现对动态经济调度问题的求解。基于IEEE 39和IEEE 118节点测试系统的算例,表明该文所提方法能够有效求解电力系统动态经济调度优化问题,与遗传算法和粒子群算法相比,该方法的计算结果和稳定性均更优,具有很好的应用前景。     

Quasi-oppositional differential evolution for optimal reactive power dispatch

This paper presents quasi-oppositional differential evolution to solve reactive power dispatch problem of a power system. Differential evolution (DE) is a population-based stochastic parallel search evolutionary algorithm. Quasi-oppositional differential evolution has been used here to improve the effectiveness and quality of the solution. The proposed quasi-oppositional differential evolution (QODE) employs quasi-oppositional based learning (QOBL) for population initialization and also for generation jumping. Reactive power dispatch is an optimization problem that reduces grid congestion with more than one objective. The proposed method is used to find the settings of control variables such as generator terminal voltages, transformer tap settings and reactive power output of shunt VAR compensators in order to achieve minimum active power loss, improved voltage profile and enhanced voltage stability. In this study, QODE has been tested on IEEE 30-bus, 57-bus and 118-bus test systems. Test results of the proposed QODE approach have been compared with those obtained by other evolutionary methods reported in the literature. It is found that the proposed QODE based approach is able to provide better solution.     

基于混沌粒子群优化方法的电力系统无功最优潮流

针对电力系统无功最优潮流问题,提出一种混沌粒子群优化(CPSO)方法,以克服粒子群优化(PSO)方法容易早熟而陷入局部最优解的缺点。该方法结合混沌变量良好的遍历特性及混沌优化的特点,对即将重合而引起搜索能力下降的粒子赋予混沌状态搜索,其余粒子仍以常规PSO方法搜索,从而提高PSO方法的寻优性能。通过对IEEE6,IEEE14,IEEE30和IEEE118测试系统无功最优潮流问题的计算及分析,表明CPSO方法具有很高的搜索效率和诱人的应用前景。     

基于成本最优的含储热光热电站与火电机组联合出力日前调度

含储热光热发电的优势体现为良好的出力可控性和可调度性,合理调度光热发电能够有效降低系统运行成本。以成本最优为目标,从光热电站的光电转换特性分析角度出发,在计及各项运行约束的基础上,提出含储热光热电站与火电机组联合出力调度策略。该策略综合考虑火电机组发电成本、光热发电并网消纳的环境效益和运行维护成本、系统旋转备用成本以及电网安全运行约束等因素,从而确定光热电站在既定储热容量下的最优出力调度策略。基于遗传算法,通过IEEE 30节点算例验证了所提方法的可行性与有效性。     

基于改进粒子群优化算法的电力系统有功最优潮流

提出了一种基于改进粒子群优化算法的有功最优潮流模型及求解方法,采用了自适应罚函数法处理最优潮流问题的各种约束条件。通过对IEEE-30节点系统的仿真计算,并且与遗传算法进行比较,验证了提出的模型和方法的有效性。     

Optimal reactive power dispatch using quasi-oppositional teaching learning based optimization

This paper presents a newly developed teaching learning based optimization (TLBO) algorithm to solve multi-objective optimal reactive power dispatch (ORPD) problem by minimizing real power loss, voltage deviation and voltage stability index. To accelerate the convergence speed and to improve solution quality quasi-opposition based learning (QOBL) concept is incorporated in original TLBO algorithm. The proposed TLBO and quasi-oppositional TLBO (QOTLBO) approaches are implemented on standard IEEE 30-bus and IEEE 118-bus test systems. Results demonstrate superiority in terms of solution quality of the proposed QOTLBO approach over original TLBO and other optimization techniques and confirm its potential to solve the ORPD problem.     

A hybrid genetic algorithm-interior point method for optimal reactive power flow

By integrating a genetic algorithm (GA) with a nonlinear interior point method (IPM), a novel hybrid method for the optimal reactive power flow (ORPF) problem is proposed in this paper. The proposed method can be mainly divided into two parts. The first part is to solve the ORPF with the IPM by relaxing the discrete variables. The second part is to decompose the original ORPF into two sub-problems: continuous optimization and discrete optimization. The GA is used to solve the discrete optimization with the continuous variables being fixed, whereas the IPM solves the continuous optimization with the discrete variables being constant. The optimal solution can be obtained by solving the two sub-problems alternately. A dynamic adjustment strategy is also proposed to make the GA and the IPM to complement each other and to enhance the efficiency of the hybrid proposed method. Numerical simulations on the IEEE 30-bus, IEEE 118-bus and Chongqing 161-bus test systems illustrate that the proposed hybrid method is efficient for the ORPF problem.     

基于负荷均衡加载的电力系统分布式经济调度策略

在构建以新能源为主题的新型电力系统背景下,电网面临以电动汽车为代表的电气化交通负荷剧增的巨大挑战。针对上述问题提出一种负荷均衡优化模型,将负荷均衡后的集群电动汽车依次并入电网。然后应用多智能体一致性算法,以发电机组的增量成本和集群电动汽车的增量效益作为一致性变量,设计一种集群电动汽车参与电力系统经济调度的算法,通过分布式优化方式解决经济调度问题。建立4种典型的仿真情景,分别验证集群电动汽车分步参与电力系统分布式优化调度的有效性、对不同通信拓扑和功率受约束情况的适用性以及分布式优化算法在集群电动汽车参与经济调度时“即插即用”的能力。在IEEE 39节点系统上进行算例仿真,验证了策略的有效性。